Interlaced video is a technique that is commonly used in video recording systems and in television broadcast systems. The purpose of interlaced video is to increase the quality by doubling the line resolution, i.e., the vertical resolution, without doubling the required bandwidth. In interlaced video formats, a video frame 10, see FIGS. 1 and 2, includes two sets of horizontal video lines 12, 14, also referred to as fields, captured at different points in time. Each set of video lines 12, 14, or each field, comprises substantially half of the lines that are forming the full video frame. One basic way to display an interlaced video frame would be to display a first field 12, e.g., including odd numbered lines, at one instant and then display a second field 14, e.g., including even numbered lines, at the next instant.
In order to display the video in progressive or noninterlaced format, interlaced video must be de-interlaced. De-interlacing requires two fields 12, 14, to be merged into one de-interlaced video frame 16, see FIG. 3. However, the two fields 12, 14, are captured at different points in time and a video sequence including motion will present a “combing” effect where alternate lines represents an image that is slightly displaced from each other.
There are various methods for de-interlacing video, each presenting some kind of artifacts or other problems. The various methods may be grouped into field combination de-interlacers, field extension de-interlacers, and motion detecting de-interlacers. Field combination de-interlacers take the lines of the two fields 12, 14, and combine them into one de-interlaced video frame 16 which is then displayed. Examples of specific methods are weaving, blending, selective blending, and telecide style algorithms. Field extension de-interlacers take each field, i.e., half the lines of a frame, and extend them to the entire screen to make a frame. Examples of specific methods are half-sizing and line doubling. Motion detecting de-interlacers often uses both of the above methods combined with edge detection and other techniques. Some of the methods are able to generate video having twice the frame rate of the original, using the fact that the fields are sent at twice the rate of the frame rate and some interpolating algorithms. A problem with the methods generating video having twice the frame rate is that they either produce video of pour quality or is very complex and computationally heavy.